Allosterically targeting EGFR drug-resistance gatekeeper mutations.
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ABSTRACT:
SUBMITTER: Spellmon N
PROVIDER: S-EPMC5542946 | biostudies-literature | 2017 Jul
REPOSITORIES: biostudies-literature
Publications
Allosterically targeting EGFR drug-resistance gatekeeper mutations.
Spellmon Nicholas N Li Chunying C Yang Zhe Z
Journal of thoracic disease 20170701 7
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Project description:Osimertinib, a mutant-specific third-generation EGFR tyrosine kinase inhibitor, is emerging as the preferred first-line therapy for EGFR-mutant lung cancer, yet resistance inevitably develops in patients. We modeled acquired resistance to osimertinib in transgenic mouse models of EGFRL858R -induced lung adenocarcinoma and found that it is mediated largely through secondary mutations in EGFR-either C797S or L718V/Q. Analysis of circulating free DNA data from patients revealed that L718Q/V mutations almost always occur in the context of an L858R driver mutation. Therapeutic testing in mice revealed that both erlotinib and afatinib caused regression of osimertinib-resistant C797S-containing tumors, whereas only afatinib was effective on L718Q mutant tumors. Combination first-line osimertinib plus erlotinib treatment prevented the emergence of secondary mutations in EGFR. These findings highlight how knowledge of the specific characteristics of resistance mutations is important for determining potential subsequent treatment approaches and suggest strategies to overcome or prevent osimertinib resistance in vivo. SIGNIFICANCE: This study provides insight into the biological and molecular properties of osimertinib resistance EGFR mutations and evaluates therapeutic strategies to overcome resistance. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/10/2017/F1.large.jpg.
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Project description:EGFR is a major anticancer drug target in human epithelial tumors. One effective class of agents is the tyrosine kinase inhibitors (TKIs), such as gefitinib and erlotinib. These drugs induce dramatic responses in individuals with lung adenocarcinomas characterized by mutations in exons encoding the EGFR tyrosine kinase domain, but disease progression invariably occurs. A major reason for such acquired resistance is the outgrowth of tumor cells with additional TKI-resistant EGFR mutations. Here we used relevant transgenic mouse lung tumor models to evaluate strategies to overcome the most common EGFR TKI resistance mutation, T790M. We treated mice bearing tumors harboring EGFR mutations with a variety of anticancer agents, including a new irreversible EGFR TKI that is under development (BIBW-2992) and the EGFR-specific antibody cetuximab. Surprisingly, we found that only the combination of both agents together induced dramatic shrinkage of erlotinib-resistant tumors harboring the T790M mutation, because together they efficiently depleted both phosphorylated and total EGFR. We suggest that these studies have immediate therapeutic implications for lung cancer patients, as dual targeting with cetuximab and a second-generation EGFR TKI may be an effective strategy to overcome T790M-mediated drug resistance. Moreover, this approach could serve as an important model for targeting other receptor tyrosine kinases activated in human cancers.
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Project description:PurposeMutant selective irreversible pyrimidine-based EGFR kinase inhibitors, including WZ4002, CO-1686, and AZD9291, are effective in preclinical models and in lung cancer patients harboring the EGFR T790M gefitinib/erlotinib resistance mutation. However, little is known about how cancers develop acquired resistance to this class of EGFR inhibitors. We sought to identify and study EGFR mutations that confer resistance to this class of agents.Experimental designWe performed an N-ethyl-N-nitrosourea (ENU) mutagenesis screen in EGFR-mutant (sensitizing alone or with concurrent EGFR T790M) Ba/F3 cells and selected drug-resistant clones. We evaluated the sensitivity of EGFR inhibitors in models harboring drug-resistant EGFR mutations.ResultsWe identified 3 major drug resistance mutations. EGFR L718Q, L844V, and C797S cause resistance to both WZ4002 and CO-1686 while, in contrast, only EGFR C797S leads to AZD9291 resistance. Cells containing an EGFR-sensitizing mutation, Del 19 or L858R, in conjunction with L718Q, L844V, or C797S retain sensitivity to quinazoline-based EGFR inhibitors, gefitinib and afatinib. The C797S mutation, in the presence of Del 19 or L858R and T790M, causes resistance to all current EGFR inhibitors, but L858R/T790M/C797S remains partially sensitive to cetuximab which leads to disruption of EGFR dimerization.ConclusionsOur findings provide insights into resistance mechanisms to irreversible pyrimidine-based EGFR inhibitors and identify specific genomic contexts in which sensitivity is retained to existing clinical EGFR inhibitors. These findings will guide the development of new strategies to inhibit EGFR.
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Project description:BackgroundThe epidermal growth factor receptor (EGFR) inhibitors represent the first-line therapy regimen for non-small cell lung cancer (NSCLC). Most of these inhibitors target the ATP-site to stop the aggressive development of NSCLC. Stabilization of the ATP-binding on EGFR is difficult due to autophosphorylation of the EGFR domain. This leads to activation of nonintrinsic influence of the tumor microenvironment and expression of anti-apoptotic pathways and drug resistance.MethodsThe NSCLC related literature search was carried out using online databases such as Scopus, Web of Sciences, PubMed, Protein Data Bank and UniPort for the last ten years and selected articles are referred for discussion in this review.ResultsTo overcome the problem of mutations in NSCLC, the allosteric site of EGFR was targeted, which shows significant therapeutic outcome without causing resistance. Compounds like EAI001, EAI045 JBJ-04-125-02, DDC4002 and a series of small molecules with an affinity towards the EGFR allosteric site are reported and are under the investigational stage. These compounds are categorized under fourth-generation anti-NSCLC agents.ConclusionComposition of this review highlights the advantage of inhibiting allosteric site in the EGFRTK receptor domains and presents a comparative analysis of the new fourth-generation anti-NSCLC agents to overcome the drug resistance.
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Project description:Protein kinases are therapeutic targets for human cancer. However, "gatekeeper" mutations in tyrosine kinases cause acquired clinical resistance, limiting long-term treatment benefits. mTOR is a key cancer driver and drug target. Numerous small-molecule mTOR kinase inhibitors have been developed, with some already in human clinical trials. Given our clinical experience with targeted therapeutics, acquired drug resistance in mTOR is thought likely, but not yet documented. Herein, we describe identification of a hot spot (L2185) for drug-resistant mutations, which is distinct from the gatekeeper site, and a chemical scaffold refractory to drug-resistant mutations. We also provide new insights into mTOR kinase structure and function. The hot spot mutations are potentially useful as surrogate biomarkers for acquired drug resistance in ongoing clinical trials and future treatments and for the design of the next generation of mTOR-targeted drugs. Our study provides a foundation for further research into mTOR kinase function and targeting.
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Project description:A significant fraction of non-small cell lung cancer (NSCLC) cases are due to oncogenic mutations in the tyrosine kinase domain of the epidermal growth factor receptor (EGFR). Anti-EGFR antibodies have shown limited clinical benefit for NSCLC, whereas tyrosine kinase inhibitors (TKIs) are effective, but resistance ultimately occurs. The current landscape suggests that alternative ligands that target wild-type and mutant EGFRs are desirable for targeted therapy or drug delivery development. Here we evaluate NSCLC targeting using an anti-EGFR aptamer (MinE07). We demonstrate that interaction sites of MinE07 overlap with clinically relevant antibodies targeting extracellular domain III and that MinE07 retains binding to EGFR harboring the most common oncogenic and resistance mutations. When MinE07 was linked to an anti-c-Met aptamer, the EGFR/c-Met bispecific aptamer (bsApt) showed superior labeling of NSCLC cells in vitro relative to monospecific aptamers. However, dual targeting in vivo did not improve the recognition of NSCLC xenografts compared to MinE07. Interestingly, biodistribution of Cy7-labeled bsApt differed significantly from Alexa Fluor 750-labeled bsApt. Overall, our findings demonstrate that aptamer formulations containing MinE07 can target ectopic lung cancer without additional stabilization or PEGylation and highlights the potential of MinE07 as a targeting reagent for the recognition of NSCLC harboring clinically relevant EGFRs.
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2014-12-17 | E-GEOD-45649 | biostudies-arrayexpress
Project description:BackgroundSelpercatinib (LOXO-292) and pralsetinib (BLU-667) are highly potent RET-selective protein tyrosine kinase inhibitors (TKIs) for treating advanced RET-altered thyroid cancers and non-small-cell lung cancer (NSCLC). It is critical to analyze RET mutants resistant to these drugs and unravel the molecular basis to improve patient outcomes.Patients and methodsCell-free DNAs (cfDNAs) were analyzed in a RET-mutant medullary thyroid cancer (MTC) patient and a CCDC6-RET fusion NSCLC patient who had dramatic response to selpercatinib and later developed resistance. Selpercatinib-resistant RET mutants were identified and cross-profiled with pralsetinib in cell cultures. Crystal structures of RET-selpercatinib and RET-pralsetinib complexes were determined based on high-resolution diffraction data collected with synchrotron radiation.ResultsRETG810C/S mutations at the solvent front and RETY806C/N mutation at the hinge region were found in cfDNAs of an MTC patient with RETM918T/V804M/L, who initially responded to selpercatinib and developed resistance. RETG810C mutant was detected in cfDNAs of a CCDC6-RET-fusion NSCLC patient who developed acquired resistance to selpercatinib. Five RET kinase domain mutations at three non-gatekeeper residues were identified from 39 selpercatinib-resistant cell lines. All five selpercatinib-resistant RET mutants were cross-resistant to pralsetinib. X-ray crystal structures of the RET-selpercatinib and RET-pralsetinib complexes reveal that, unlike other TKIs, these two RET TKIs anchor one end in the front cleft and wrap around the gate wall to access the back cleft.ConclusionsRET mutations at the solvent front and the hinge are resistant to both drugs. Selpercatinib and pralsetinib use an unconventional mode to bind RET that avoids the interference from gatekeeper mutations but is vulnerable to non-gatekeeper mutations.
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